HAEMACHATES :
Variety of agate .

HAEMATITE :
Synonym of Hematite.

HAFNEFJORDITE :
Variety of Labradorite.

HAKIK :
General term designating the agates in India.

HAMBERGITE :
Etym.  : named after a Swedish mineralogist
Collector’s gemstone.
Basic beryllium borate
Be₂(OH)BO₃ 
Physical and optical properties :
- Colours : Colourless to greyish-white, yellowish white
- Transparency : transparent to translucent
- Lustre : vitreous to dull
- Hardness : 7.5
- S.G. : 2.35
- R.I. : 1.55 - 1.63 (Birefr. : 0.072 to 0.080)
- biaxial positive
- System : orthorhombic
Occurrences :
Madagascar, Norway, India (Kashmir)

HANCOCHITE :
Sort of Epidote containing Pb and Sr.

HAN YU :
Chinese Term for a Jade of the time of the Han dynasty.
Term equaly used to designate commercially a Jade artificially tinted.

HARD FAHLUNITE :
Synonym of Iolite (Cordierite).

HARD SPAR :
Old synonym of Corundum or of Andalousite.

HARLEQUINE OPAL :
Variety of Opal, generally on white background, containing angular coloured spots resembling a mosaic.

HARMOPHANE :
Variety of Corundum.

HARTSPATH :
Old German name. Synonym of Andalousite.

HATCHET STONE :
American name for a sort of Nephrite.

HAUYN :
German for Haüynite .

HAÜYNITE or HAÜYNE:
Silicate with sulphate belonging to the sodalite group.
One of the components  of Lapis-lazuli .
[(Na,Ca)_4-8Al₆Si₆O₂₄(SO₄)_1-2]
Physical and optical properties:
- Colours : brilliant blue to blue-green , also yellow or red possible
- Transparency : transparent to opaque
- Lustre : almost adamantine to vitreous
- Hardness : 5.5 to 6
- S.G. : 2.4 to 2.5
- R.I. :1.496 to 1.51
- Crystal system : cubic

HAWAIITE :
Name given to a Peridot of pale green colour found at the Isles of Hawaii.

HAWK’S EYE :
Variety of fibrous Quartz with cat’s eye effect; aggregate with fibres of crocidolite (type of hornblende) of dark grey, light blue to dark blue grey, dark greenish blue, blackish blue colour

HAYTORITE :
Chalcedony pseudomorphous after Datolite.

HEAVEN STONE :
English term for Benotoïde.

HECATOLITE :
Synonym of Moonstone.

HEDENBERGITE :
Collector’s stone.
Variety of ferric Diopside.
CaFe²⁺(SiO₃)₂
Physical and optical properties :
- Colours : brownish green, grayish green, dark green, grayish black, black.
- Transparency : transparent to opaque
- Lustre : vitreous to pearly
- Hardness : 5 to 6
- S.G. : 3.30 to 3.55
- R.I. : 1.699/1.739 - 1.728/1.757 (birefr. : 0.018 to 0.029)
- biaxial positive
- System : monoclinic

HEDGEHOG STONE :
English Name for a quartz with inclusions of needles of Goethite.

HEI-TIKI :
Amulet made out of jade (note : New Zealand jade = Nephrite) of the Maoris of New Zealand.

HELIODORE :
Yellow Beryl slightly ferriferous.
Al₂Be₃(Si₆O₁₈)
Physical and optical properties :
- Colours : slightly yellowish to greenish yellow. The yellow colour is generally attributed to a substitution of aluminium-ferric iron and, by certain authors, to a weak radioactivity.
- Transparency : transparent
- Lustre : vitreous
- Hardness : 7.5
- S.G. : 2.7
- R.I. : 1.563 - 1.582 ( Birefr : 0.007 to 0.010)
- uniaxial negative
- Pleochroism : very weak : pale yellow, pale yellowish-green.
- Crystal system : hexagonal
Occurrences :
Discovered in 1910 in Namibia in geodes of pegmatites producing equally aquamarines. Together, besides aquamarine, with Topaz and Tourmaline.
Madagascar, Ukraine, Afghanistan, China.
Treatments :
Via a thermal treatment, the heliodore may become blue (=aquamarine) or colourless (=goshenite) but will regain its initial colour after irradiation with gamma rays.

HELIOLITE :
Synonym of aventurine Feldspar or Sun Stone.

HELIOTROPE :
Synonyms : Blood Jasper, martyrs’ stone, green jasper, blood stone.
Micro-crystalline. Belongs to the quartz group, variety of chalcedony;
Silicon dioxide
SiO₂
Physical and optical properties :
- Colour : dark green, spotted with red dots. This colour is not always stable
- Transparency : opaque
- Hardness : 6.5 to 7
- R.I. : ± 1.54
- S.G. : 2.40 to 2.91
- Fluorescence : none.
Occurrences :
India, Australia, Oregon (USA)

HELVITE :
Synonym : helvine
Collector’s stone
Mn₄Be₃(SiO₄ )₃S
Physical and optical properties :
- Colours : yellow the colour of honey, brown or green.
- Hardness : 6 to 6.5
- S.G. : 3.2 to 3.37
- R.I. : 1.739
- Crystal system : cubic

HEMACHATE :
Agate faintly coloured, spotted with red Jasper or iron-hydroxides.

HEMATINE :
Synthetic stone made of inoxydable steel containing chrome, nickel and imitating Hematite. This composition of inoxydable steel is magnetic whence natural hematite is in general not.

HEMATITE :
In French. Synonyms : ‘fer oligiste’ or ‘fer sanguin’.
Iron oxide.
Fe₂O₃
Physical and optical properties :
- Colours : grey-black steel colour with metallic reflection; very brilliant when polished. Blood Red and transparent in thin slices.
- Transparency : opaque
- Lustre : metallic
- Hardness : 5 to 6.5
- R.I. : 2.94 - 3.22 (Birefr. : -0.280)
- uniaxial negative
- S.G. : 5.26
- System : trigonal
Occurrences :
Saint Jacques de Compostella in Spain, Great-Britain (2 occurrences in Cumberland now exhausted), Brazil.
Situated in sedimentary deposits, of contact metamorphisme, in veins, …
Imitations :
Black schists, black waist-material of ovens, black glasses.
See also the Latest Gemmological News concerning hematite.

HEMATITE BRA :
Synonym of Limonite.

HEMETINE :
Commercial name of an imitation of Hematite.
At the start, one used a sulphur of lead ; the more recent material used as an imitation is iron with titanium oxide, giving a red-brown streak on a de-polished porcelain plaque.
Hardness 2.5 to 6 / S.G. : 4 to 7

HEMIMORPHITE :
Synonym (old ) : calamine, galmei.
Zn₄Si₂O₇(OH)₂.H₂O
Hydro-silicate of zinc.
Stone only cut as a cabochon and sometimes confounded with Smithsonite.
Physical and optical properties :
- Colours : Colourless, grey, yellowish, brown, greenish, sky blue.
- Transparency : transparent to translucent
- Hardness :  5
- S.G. : 3.30 to 3.50
- R.I. : 1.614 – 1.636 (Birefr. : 0.022)
- Biaxial positive
- Crystal system : orthorhombic

HENWOODITE :
Synonym of Turquoise.

HERBEKITE :
Variety of jasper.

HERMANNITE :
Synonym of Rhodonite.

HERRERITE :
Smithsonite of a light steel blue or copper green colour from Albarradon (Mexico).

HESSONITE :
Synonyms : Essonite ; Pierre de Cannelle (French term).
Variety of Grossular garnet.
Physical and optical properties:
- Colours : orange, yellowish, red, brown.
- Hardness : 7.
- S.G. : 3.5 to 3.7
- R.I. : 1.74 to 1.76
Confusions :
Hyacinth Zircon (red-brown), tourmaline, spinel, padparadscha sapphire, yellow to orange-brown sapphire.

HEXAGONITE :
Variety of Tremolite or belongs to the group of the Hornblendes.
Silicate of magnesium.
Physical and optical properties :
- Colours : bluish to reddish, to violet
- Transparency : Transparent to translucent
- Hardness : 5 to 6
- S.G. : 2.9 to 3.4
- R.I. : 1.610 - 1.629

HIDDENITE :  
Etym. : named after the mineralogist William Earl Hidden (1853-1918).
Chromiferous Spodumene of more or less sustained green (to rarely emerald green) colour.
Well formed crystals extremely rare & of small size.
LiAlSi₂O₆
Physical and optical properties :
- Colours : pale green to (rarely emerald) green, green yellowish, dark green, brownish green.
- Hardness : 6 to 7
- R.I. : 1.655 - 1.680 (Birefr. : +0.015)
- S.G. : 3.16 to 3.20
- pleochroism :Trichroïc
- System : monoclinic
- Cleavage : perfect
- becomes red under the Chelsea filter
Imitation :
Kunzite irradiated with cobalt becomes green. The colour disappears after a few days under sunlight. Recognition : blood red under Chelsea filter.
Confusions :
Green Diopside.

HIMBEERSPATH :
Synonym of Rhodocrosite.

HMAW SIT SIT :
Or Maw-sit-sit.
Burmese Name for a Jadeite-albite , of green colour (or seldom mauve), sometimes with yellowish tones and almost always with black spots.

HODGKINSONITE :
Etym. : named for H. H. Hodgkinson, assistant underground supervisor of Franklin mine who discovered the mineral.
Collector’s stone.
Mn(ZnOH)₂SiO₄ 
Physical and optical properties :
- Colours : pink to purple, orange brown
- Transparency : transparent to opaque
- Lustre : vitreous
- Hardness : 4.5 to 5
- S.G. : 3.91
- R.I. : 1.720 - 1.746 (birefr. : 0.026)
- biaxial negative
- System : monoclinic.

HOHLSPATH :
German name. Synonym of Chiastolite.

HOLLOWSPAR :
Synonym of Chiastolite.

HOLZOPAL :
German term for wood opal . Variety of Opal ( French : Opale de bois).

HOLZSTEIN :
German name. Variety of Chalcedony, or term for designating petrified or fossilized wood.

HONAN JADE :
Name given by the English to a mixture of Jade and of Quartz, or of Serpentine and of Soapstone. From the province of Honan, China.

HOPE SAPPHIRE :
Prohibited appellation designating originally a synthetic blue spinel and, by extension, a synthetic blue sapphire coloured by cobalt oxide.

HORATIO DIAMOND :
Prohibited appellation for a quartz of Arkansas.

HORNSTONE :
For the Anglo-Americans, variety of (silex) quartz of often brownish colour, of non-gem quality.

HORNSTEIN :
German Term designating a crypto-crystalline quartz to be classified amongst the jaspers and chalcedonies, of the colours grey or brown, sometimes green, black or yellow, rarely yellowish red.

HOT SPRINGS DIAMOND :
Prohibited appellation for a rock crystal.

HOWDENITE :
Variety of Chiastolite with design resembling to plants and originating from Southern Australia.

HOWLITE :
Etym. : named after Henry How of Nova Scotia when he first described it in 1868.
Borosilicate

Ca₂B₅SiO₉OH₅
Physical and optical properties :
- Colours : snow white with black and brown dark veins.
- Transparency : opaque to translucent
- Hardness : 3.5 to 4.5
- S.G. : 2.53 to 2.59
- R.I. : average 1.598 ; 1.586 – 1.605 (n_y : 1.598) (birefr. : 0.020)
- biaxaial negative
- System : monoclinic
- under S.W.U.V. : brown-yellow
Treatments :
Tinted artificially in turquoise blue.
Serves sometimes as an imitation of turquoise.

HSI JADE :
Chinese Name for a Jade of light colour.

HSIEH JADE :
Chinese Name for a Jade the of colour of black ink.

HSIU YEN :
Chinese Name for a green or white Jasper sometimes sold to tourists for a Jade.

(HUNGARIAN) CAT’S EYE :
Inferior quality of Quartz cat’s eye of greenish yellow or pale grey colour; generally tinted to reinforce the colour and coming from Bavaria ( and not from Hungary )

HUIZO :
Peruvian Name for a Lapis-lazuli.

HYACINTH:
Synonym : Jacinthe.
Reddish Silicate of zircon. (See Zircon)
Physical and optical properties :
- Colour : Different tones of red, orange and brown.
- Hardness : 6.5 to 7.5
- R.I. : 1.777 to 1.987 ( Birefr : + 0.059)
- S.G. : 3.90 to 4.71
- Pleochroism : very weak: red, light brown.
- Fluorescence : faint dark yellow.
Remarks :
Term equally employed for designating a garnet or a spinel.

HYACINTH BRA :
Prohibited appellation for a Vesuvianite.

HYACINTH of CALIFORNIA :
Prohibited appellation for a Hessonite.

HYACINTH of SRI LANKA :
Prohibited appellation for a garnet.

HYACINTH of COMPOSTELLA :
Prohibited appellation for a red opaque garnet or for a hematoïde quartz or even for a red gypsum or a brownish citrine.

HYACINTHE DU VESUVE :
French term. Used to designate a variety of Idocrase or Vesuvianite of brown or yellow-honey colour.

HYACINTH GARNET :
Grossular Garnet of colour orange, reddish-brown, red (old term; now hyacinth means red-brown zircon).

HYACINTHINE :
Variety of Idocrase.

HYACINTHOÏDE :
Synonym of Hessonite.

HYACINTHOZONES :
Name given to a beryl the colour of a blue sapphire.

HYACINTH SPINEL :
Synonym of Rubicelle (French).

HYACINTH TOPAZE :
Prohibited appellation as Synonym of Zircon.

HYALINE :
Variety of milky Quartz.

HYALITE :
Variety of Opal, ordinary colourless, or almost colourless fire Opal, transparent, giving only a very weak fire.
Equally synonym of Axinite (Source : Chiser).

(HYALITE) OPAL :
Colourless transparent opal that shows but very little play of colours.

HYALITHE :
Variety of opaque glass resembling to porcelaine.
Generally of a black, green, or red colour.

HYALOMELANE :
Variety of natural glass (tektite) from Labrador.

HYALOSIDERITE :
Peridot of olive green colour containing a lot of iron.

HYDRARGILLITE (of Cleaveland):
Synonym : Gibbsite
Looks like howlite.
Al(OH)₃ 
Physical and optical properties :
- Colours : Colourless to white.
- Hardness : 2.5 to 3
- S.G. : 2.3 to 2.4
- R.I. : 1.567 - 1.589 (birefr. : 0.018)
- biaxial positive
- Crystal system : monoclinic
- Occurs as spherical rounded aggregates
Treatments :
Tinted artificially blue the colour of turquoise.
Serves as an  imitation of turquoise and carries the commercial name of Neotürkis (German) or Neo-turquoise.

HYDROLITE :
Synonym of Enhydre.

HYDROPHANE or (HYDROPHANE) OPAL:
Variety of very porous Opal, opaque in air and transparent immerged in water.
Physical and optical properties :
Idem to opal.
Remarks :
The play of colour of hydrophane is only remarked when immerged in water.

HYDROPHITE :
Variety of Serpentine.

HYDROPITE :
Variety of Rhodonite or altered Rhodonite.

HYDROPYRITE :
Synonym of Marcassite.

HYDROTACHYLYTE :
Vitreous variety of Labradorite.

HYENA :
Name given in ancient times to a sort of Agate of which the lined aspect made it resemble to the skin of a hyena.

HYPERSTHENE :
Collector’s stone
It forms a solid solution series with enstatite and ferrosilite (A solid solution series occurs when two or more elements can substitute for each other in a crystal structure without much alteration of the structure); Hypersthene is intermidiate in this series and more rich in iron (around 50%) ; the other end member ferrosilite is the most rich in iron.
(Fe,Mg)SiO₃ 
Physical and optical properties :
- Colours : very dark green, brown, black
- Transparency : hardly ever transparent, translucent
- Hardness : 5 to 6
- S.G. : 3.4 to 3.5
- R.I. : 1.715 - 1.731 (rich in iron) ; 1.673 – 1.683 (poor in iron) (Birefr. : 0.010 to 0.016)
- biaxial negative
- System : orthorhombic.
Occurrences :
Norway, Greenland, Bavaria (Germany), Northern America, …

HYPOSCLERITE :
Green variety of Albite.